[INDIA]Building heavy duty Chasis for Power Amps.
As me and Sunil were meandering along the bylanes of SP Road hunting for heatsinks and chasis we struck upon an Idea. Why not buy Al extrusions bars sheets and make them. We got the resources, but the real issue is quantity.
There are various Al extrusions avaialble at SP road, including the ones specifically meant for heatsinks. Anodised, nice rugged and heavy. They sell only as whole bars. (ie 6ft(8kg) or 12 Ft) and the price is 170 INR per Kg for the heatsinks. (these are 100mm wide, with around 6-7mm thick base, 3mm thick fins and a seperation of about 8-10mm between fins..the fins are about 25 mm high..!)
There are 98mm bars available with a thickness ranging from 4mm, 6mm , 8mm...these too are 12 feet long pieces. The cost for a piece was around 960INR.
I've attached a drawing (made in word, so please excuse the quality) of what we propose to do, just one of the ideas..! This is for a multichannel Gainclone.! If we can generate a group order we shall talk to the ppl at the shop. They have contacts to Al worksops who can fabricate this. Rt from cutting, drilling, milling etc etc to anodising or powder coating.
The cost of materials worksout to..
for a chasis similar to the one in the doc...
2feet of heatsink = 340INR, (2.6Kg) (sides)
2Ft 6 inches Al bar = 200INR (1.5kg) (front, back)
2*(1ftx1ft 4inches) = 250-500 (0.5kg-1.5kg depending on thickness) (top and bottom)
Total = 800INR - 1250INR (4.6 5.6 kg)
Adding an equal amout for fabrication and knick knacks like L junctions, nuts, etc etc...that would be one hell of a chasis for around 2500INR..!!
If we can get enough ppl, we might get a good bargain on the fabrication costs as well..!!
What do you guys think..?
Re: [INDIA]Building heavy duty Chasis for Power Amps.
Very interesting stuff. Thanks for the heads-up. I'll try to put in my ten-paise worth of reactions and data points.
In your case, you will get the raw stock at about Rs.225 for 12" (1.33Kg weight), and then you'll have to do the finishing (filing, deburring), and black anodising separately. And anodising is quite expensive, though I don't have ready figures.
I have bought another section which was 7.5" wide (18.5cm or so) for Rs.25/cm length. That one had fins which were slightly shorter (maybe 2cm tall?) and thicker. That's the widest section I've seen at L.Road.
Personally, I think I'd rather pay the extra price and buy ready-made heatsinks retail than go looking for a service provider for each step. And from experience I can tell you that simply transporting stuff from one place to another can eat up money in just fuel costs, tempo fares, auto fares, cab fares, etc. We've spent a few thousand rupees in the last few months in just conveyance of heavy and/or delicate items this way. Once I factor in those costs, the raw-stock option does not appear all that cheap. My friend visited Jeetubhai (Peerless drivers) a fortnight ago, and spent more than Rs.100 on just that visit.
And I'm really surprised that you need to do a bulk purchase for these sections. I have often walked around in shops in New Bombay and picked up one metre of this section and half metre of that for a few rupees. They simply cut a piece from one of the 12ft-long pieces and give it to me. Needless to say, the retail rate is higher than the full-length rate, but who cares?
When we were interacting with Uncle Harry for getting custom-built knobs made, I asked him once about making just 20 pieces of 50mm knobs. He said that this would be very difficult, because Al rods must be bought in 12-ft-long lengths, and so on. Then, in front of me, he called his Al supplier and that guy said that he'd happily sell any length... even a half-metre length. Uncle Harry was surprised but he rapidly confirmed to me that 12-foot-long rods were not needed. This seems to be the universal story.
I feel that if you actually try to get a few chassis made this way, you'll realise that there are severe problems on two fronts:
Sorry for sounding like a party-pooper. I really appreciate your enthusiasm, don't misunderstand me. If you can address these issues, then go right ahead.
Many thanks Tarun for the long indepth reply..!
here is what I thought..!
500 for a finished black anodised peice..
225 for an unfinished raw piece....!!
That means labour and finishing costs are equivalent to that of the material itself...
That is the rough estimate which I took too..!! So roughly the final product will be twice your material cost.. (accounted)
Next...the fab which will do the work for us...!!
Looking at the design, in its current form all you need is a lot of holes drilled in various sizes. No others shape cutouts needed..We plan to use all MX connectors and stuff...so that would remain a standard across INDIA(if it comes to that) and they are easily available..I would have preferred a handle to be made on the front plate on either side..but that would call for some milling and hence kept it away.. (alternatively we will lookout for some nice industrial grade door handles..either in Al or brushed steel...)I guess any machine shop with a good drill and premarked pieces would be able to drill holes pretty neatly..! then you need L sections cut out to specific lengths to fasten and strengthen the joints...again you need holes drilled and threaded for the purpose.. (One can even consider Araldite...or there was another green coloured varient, which was very common in SPACE industry and they used it for almost everything...!! only thing it was required to be cured in a owen)
Else there are couple of small workshops within a radius of 100mts from this shop.. so transportation shouldnt be a major ptoblem.!
But if we could get say 3-4 orders we could get a slight advantage in bargaining..even if its a small work shop..!
And since its a minimalist design, quality might be easy to acheive...
Ajju, I'm certainly interested, because right now it's imerative for me to cover up my gainclones or else I get thrown out of the house ;)
The only problem is, I'm using a dual-mono setup, with the two channel grounds separated and meeting only at the source end. That's why I was thinking of a metal-wood combination for the box, and use a wooden section for the base and back panel so that I can safely bolt the heatsinks/connectors to the wood without shorting the negative supplies or the grounds. Also wood would give it a touch of class, even if it's only veneered MDF ;)
Is part wood part metal construction an option for you?
Ajju, this sounds like a terrific idea... in fact, I thought of doing it and actually bought the heatsink extrusions and metal sheet sold at Maruthi metals. They're still collecting dust coz I haven't the time to work on 'em. Besides, I'm leaving for the US to pursue an MS... so that means I'll have to bid my amps and speakers goodbye :bawling:
Tarun's right, you may need access to CNC equipment to get proper angles & stuff. Otherwise, you'll need to find someone who has a lot of experience with regular tools, and they're hard to come by. I tried very hard to find some place which will just cut a rectangular hole in a piece of aluminium sheet (2mm thick). Not a soul would touch it, they looked at the aluminium as though it was transported from the future. Ah well... maybe I was looking in the wrong places, I never tried any place in Peenya. But then I'll bet they will only work with "Large orders", so Ajju, here's your chance! Find enough people for a "group order" of maybe 10-15 and be prepared to sweet talk some machine shop owner to help you out.
Good luck on your chassis project. I only wish I could be around to participate...
I've attached a doc which has another design. Unfortunately its still stuck at the drawing board.!
Its been pending for a while now..!
Where is Maruthi metals. Did you buy them in bulk or as pieces of required length..!
Yes Peenya is one place to explore..Only trouble i have is the language..Let me see if i can get some one who can understand and speak local language..!
btw...wish u good luck and the very best for ur MS..!
Many thanks for the moral support.:)
that design looks good. Only problem is we'll have to find a guy who does aluminium bevelling in small numbers. Or we could use wood for the top and bottom and do the bevelling ourselves.
How come you've mentioned Mahavir Aluminium? Do they have an outlet in Bangalore?
BTW, Maruti metals is in SP road. Just before you enter SP road from the Om-electronics side, there is a lane that branches off to the left, before Om. Take that lane, it's at the beginning of that lane. He's a good chap, I bought extrusions for heatsinks from him. He cut the pieces to the size I wanted.
Yes, Precisely. Al bevelling is an issue...
Actually i was thinking of using wood or Acrylic to work with..!!
Anyways first i'll see if i can persuade some machine shop to do the job for us. I'll also try some expt getting extrusions from Mahavir..!!
Ashwin told me where Maruthi Metals is. Anyway, I bought the extrusions cut to size, he charges a nominal cutting fee. Be sure to go early in the day, if it's close to getting dark, they may not get it cut for you.
Peenya: I suppose most of them would understand Hindi as well as Kannada.
There are supposed to be some chemical agents one can use to get an anodized surface. Couple that with a wire brush and I think it shd be good.
Thanks for wishing me luck! I'll do my best.
|All times are GMT. The time now is 02:44 AM.|
Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 17.65%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio